This is the concept of early customers as stakeholders.
You can be upfront with people by saying, "Hey, I've looked into your needs and painful problems and I really want to serve you. I want to build this solution. But it costs money. Here's an example (show mark up) of what I have in mind. If I get x number of people to buy now, I'll build it. You can even get lifetime access (or some substantially reduced price) for taken on the risk and believing in me".
I think all those people who discount this method of serving customers are letting their fear of rejection get hold of them.
It's okay!
Fear is a natural reaction of the lizard brain; there's nothing to be afraid of.
But those of us that have tried this method and have seen how willing people are to work with you to build a solution (if your "heart" is in the right place, i.e. to serve them), know it works.
Seth Godin has a talk about "shipping on time" and just getting it out there to let the market decide (that's totally worth seeing).
(From ForaTV's channel, "Overcoming The Lizard Brain" - https://www.youtube.com/watch?v=XqozprFZ_38 )